The present invention relates to environmental protection of elongate members such as cables and conductors. More particularly, the invention relates to methods and apparatus for easily and reliably inserting such a member through an environmental barrier and sealing the barrier to the member in a manner which preserves the integrity of the barrier.
Technologies for sealing conduits to barriers have been known for many years, ranging from the simple and mundane (from caulking compound to wires sealed through the base of an incandescent light bulb) to the very sophisticated (mechanical couplings into high vacuum apparatus). Requirements in the telecommunications industry may not be the most harsh, but they do present unique demands which heretofore have not been easily satisfied. That is, it is common to pass a cable through a barrier, such as a building wall or a splice closure, and to assure that the cable is sealed to the barrier so that the "inside" is protected from the elements on the "outside". However, such seals are regularly required by the thousands, so that speed, efficiency, reliability, versatility, and ease of use become very important. Modern practices leave much room for improvement.
To give a specific example, telephone cables often must be opened and spliced in locations where the resulting cable joint would be exposed to the elements. Splice housings or cable closures are commonly employed to remedy this problem. Ports in the closure admit the wires or cables and the ports include seals which protect the interior of the closure from the outside elements. To seal such ports to the wires, for example, with caulking compound would in many cases provide a satisfactory seal, but it would be a messy, time-consuming process. In many environmental situations it would not perform at all. More sophisticated barrier seals have therefore been developed. One such configuration utilizes a thermal adhesive within a heat shrinkable tube. When heat is applied to the tube, the tube shrinks around the cable and the adhesive secures them together. This provides a fast, reliable, and easily applied barrier seal. However, it also requires a separate tool, such as a heat gun, torch, or power supply.
A need therefore remains for new and improved methods and apparatus which provide seals for elongate objects, such as wires and cables, for easily and reliably inserting them through environmental barriers and sealing them to the barriers in a manner which preserves the barrier integrity. Preferably, the seals will be essentially self-actuating, as well as reusable, so that little more will be necessary than to insert the cable through the seal, upon which the cable or wire will automatically be environmentally secured to the barrier. As such, the method and apparatus should not require the use of additional tools, and should preferably be able to provide a cold seal. Also, upon removal of the wire or cable, the seal should be able to return essentially to its original configuration so that it can be used again, as desired, for another cable.